Often in drilling an oil or gas well, drilling fluids, (commonly referred to as “mud”) are circulated through the wellbore. The drilling fluids circulate to convey cuttings generated by a drill bit to the surface, drive a down-hole drilling motor, lubricate bearings and a variety of other functions. Wellbore telemetry systems are often provided to transmit information from the bottom of a wellbore to the surface of the earth through the column of drilling fluids in a wellbore. This information might include parameters related to the drilling operation such as down-hole pressures, temperatures, orientations of drilling tools, etc., and/or parameters related to the subterranean rock formations at the bottom of the wellbore such as density, porosity, etc.
Telemetry systems generally include a variety of sensors disposed within a wellbore to collect the desired data. The sensors are in communication with a transmitter adapted to transmit the readings to another location in the wellbore or to the surface. The transmitter may operate by generating a signal using one or more of mud pulses, electric fields, magnetic fields, acoustics, or utilizing wired pipe, also disposed within the wellbore. The mud pulser might, for example be configured to generate patterns of pressure fluctuations in the mud stream that correspond to the sensed data.